What is a Thomasson?
Thomasson Archive← map

In 1972, the artist Genpei Akasegawa (1937–2014) was walking with friends in Tokyo when they climbed a set of stairs and came back down the other side. After two days of taking the same route it landed: these stairs led nowhere, bridged nothing, ascended only to descend. He began to notice others: doors sealed into walls, handrails attached to nothing, windows filled in but still framed, eaves with nothing left beneath them to protect. The city was full of them. The question was why they were still there, still cared for, still in some sense kept. Not ruin and not neglect, something more like an echo, or something vestigial. Typically capitalism doesn't allow for this sort of thing: an object preserved with apparent care long after the reason for that care has vanished.

In 1981, the Yomiuri Giants signed the American baseball player Gary Thomasson. He came with a flawless pedigree — Giants, Yankees, Dodgers — but when he arrived in Japan he couldn't hit the ball. He led the league in strikeouts. Given the fanfare around his arrival he had to stay. In practice, though, he had become a fixture. A symbol that served no purpose.

Akasegawa named his accidental objects after him.

He insisted that Thomassons were more purely art than art itself — uncreated by any artist, unsellable, fixed in place, noticed only by those willing to look. If you write the name Gary Thomasson in Japanese characters, it spells the word for hyperart.

Thing Theory

Bill Brown's 2001 essay proposes that objects become “things” and acquire a kind of presence when they stop working, when they resist or exceed their function. Thomassons are perhaps the purest urban expression of this idea.

Mono no Aware (物の哀れ)

A Japanese aesthetic concept describing the bittersweet awareness of impermanence, often translated as “the pathos of things.” Thomassons carry this quality: objects that have outlasted their moment, preserved in a kind of afterlife.

Psychogeography

Developed by Guy Debord and the Situationist International in 1950s Paris, psychogeography describes the study of how the built environment affects emotion and behavior. The dérive, an unplanned walk through the city guided by atmosphere, is the Situationist method closest to Thomasson hunting.

Akasegawa introduced the concept publicly in 1982 through a column in the magazine Shashin Jidai (Photo Times), where readers began submitting their own discoveries. The response became a cultural moment — bus tours of Tokyo Thomassons were organised, NHK covered the phenomenon, and Akasegawa's students established the Thomasson Observation Center (超芸術探査本部トマソン観測センター) in 1982 to systematise the hunt. The center's archives, built over years of collective fieldwork, remain the primary record of the original practice.

In 1986, Akasegawa joined architectural historian Terunobu Fujimori, illustrator Shinbo Minami, writer Joji Hayashi, and editor Tetsuo Matsuda to found the Street Observation Society (路上観察学会 / ROJO), a related but broader practice — cataloguing manhole covers, unusual signage, anomalous urban forms of all kinds. ROJO published Rojō kansatsugaku nyūmon (Manual on Street Observation) that same year and went on to represent Japan at the 2006 Venice Architecture Biennale.

The Thomasson boom faded in the late 1980s under the weight of its own media attention, and both groups largely went quiet. The concept lived on in literature and film — in Akasegawa's 1981 Akutagawa Prize-winning fiction, in a scene in Patlabor: The Movie (1989), and in multiple appearances in William Gibson's 1993 novel Virtual Light.

A Western revival came with the 2010 English translation of Hyperart: Thomasson by Matthew Fargo, published by Kaya Press. The volume included essays by independent art historian and curator Reiko Tomii and Japan historian Jordan Sand (Georgetown University), who placed the practice within the longer history of Tokyo's urban transformation. Sand expanded on this in his 2013 book Tokyo Vernacular: Common Spaces, Local Histories, Found Objects, which remains the most thorough academic treatment of the Thomasson phenomenon in English.

In 2012 the Thomasson Observation Center returned online, opening a Facebook archive and accepting digital submissions. In 2013 they held their 31st anniversary exhibition — the Great Thomasson Exhibition — at Shinjuku Ophthalmologist Gallery in Tokyo. In 2023, the Taipei Biennial presented over 40,000 previously unseen photographs discovered in Akasegawa's archive after his death in 2014. A revised edition of Hyperart: Thomasson is forthcoming from Kaya Press in spring 2026.

This is a public map archive built to continue the practice of collective noticing — not as a civic reporting tool, but as a structured way of paying attention to what the city preserves without knowing why.

Anyone can submit a Thomasson. Submissions are reviewed before appearing on the map. Existing entries can receive new observations over time: a Thomasson that was intact last year may have been altered or removed. The map is a record of things seen, not a guarantee of things still there.

The categories used here follow the typology Akasegawa developed: the pure staircase, the elevated object, the A-bomb type, and so on. Thomassons need not be street-facing — an object stranded at the wrong height inside a building, a switch that can no longer be reached, a door preserved through renovation into permanent inaccessibility — these qualify too.

This archive was initiated by artist Troy Briggs in 2026.